Martin Luther King's "Address to the Churches". Recorded in St. Louis in October, 1964 at a meeting of the Episcopal Society for Cultural and Racial Unity. It was pressed to vinyl, and 1200 copies were distributed in South Africa, where it was immediately banned. This recording is from one of those vinyls.
"Address to the Churches" is something of an oddity. It is materially similar to "Remaining Awake through a Great Revolution", which he delivered in 1968. Many passages are word-for-word the same, but some sections are moved around, and in the latter speech, he changes many adjectives for greater impact. In a sense, "Address to the Churches" can be viewed as a beta test for "Remaining Awake".